@code{pop-up-windows} is non-@code{nil}.
@end defopt
+@defopt even-window-heights
+This variable determines if @code{display-buffer} should even out window
+heights if the buffer gets displayed in an existing window, above or
+beneath another existing window. If @code{even-window-heights} is
+@code{t}, the default, window heights will be evened out. If
+@code{even-window-heights} is @code{nil}, the orginal window heights
+will be left alone.
+
@c Emacs 19 feature
@defopt pop-up-frames
This variable controls whether @code{display-buffer} makes new frames.